Changing Dynamics within Repeats

I have one section of my score that is 16 bars, repeated 3 times.  The only thing I want to change is the dynamics:

1x -- p

2x -- mf

3x -- ff

I have tried these two options:

1. Placing my dynamic intent in a Performance Text field above the 1st measure of the repeated section.
2. Indicating p on the pick-up note to the repeated section with mf on the pick-up to the 2nd repeat and ff on the pick-up to the 3rd repeat.
3. Unrolling the 16-bar repeat into a 48-bar section.

I am not a professional musician, just a dabbler, but visually, I think I make my intentions clear to a live performer with either option 1 or 2 (though I am not sure which would be more "technically correct").  However, neither option will make the computer play the score they way I want it to sound.  The only way I have found to do what I want to do is option 3.

There has to be a more elegant way to write this other than option 3.